Can't select Old Bootloader in IDE

I have the commom "Processor not responding" issue on a Arduino Uno clone which I'm trying to fix.
A solution one often sees is this:

"Try selecting Tools > Processor > ATmega328P (Old Bootloader)."

The Processor option does not appear under Tools for me. I am on Mac Os and have installed the latest Arduino IDE.

The old boot loader , refers to Arduino Nanos only, so you won’t find it under a UNO menu.

Do you see a port for the UNO in the tools/ ports menu ?
As you have a clone , have you installed the CH340 driver , which is often needed?

I can select the port.

The unit was working fine foe a while then suddenly it stopped uploading.
Would installing the CH340 driver possibly help the situation?

If the board is recognised, it will show in the IDE when you connect it and disappear when you disconnect it. Does that indeed happen?

If so, I have great doubts that it's a driver issue. And you will have to determine which driver is needed for your specific Uno. Clones can have any ttl-to-usb chip; it's the chip closest to the USB port.

So what did you do to the poor board that it's no longer responding :wink: What was connected? How? Please provide a wiring diagram.